Protozoans

Question 1

What are the features of protozoans?

Answer 1

Single-celled (but can live in colonies)

Eukaryotic

Motile

Heterotrophic

Complex

Question 2

What are the different structures protozoans can use for locomotion?

Answer 2

Flagella/flagellum

Cilia - beat in metachronal waves

Pseudopodia - temporary extension of the body

Question 3

How do protozoans acquire food?

Answer 3

Food is uptaken by vesicles

Lysosomes are produced in the vesicles to break down particles

Vesicle binds with cell membraine to eject waste

Some protozoans have specialised areas for uptake and removal and others can do it anywhere

Question 4

What are the different modes of food uptake via vesicles?

Answer 4

Pinocytosis - vesicle forms around the food particles. food particles diffuse through passivly (high conc outside protozoan and low conc inside)

Receptor-Mediated Endocytosis - more specific, receptors are cell membrane can detect specific things such as proteins

Phagocytosis

Question 5

What do Paramecium contain?

Answer 5

Cytostome - ciliated groove where the vesicle can only form

Cytoproct - where waste is ejected

Contractile vacuole - prevents too much water from entering the cell (this protozoan lives in freshwater

Question 6

What are the two different types of Entamoeba?

Answer 6

Entamoeba dispar and coli live in the human gut and do NOT harm the host

Entamoeba histolytica lives in the human gut and buries into the intestinal wall and can move into the blood and brain (from contaminated food and water)

Question 7

What are apicomplexans? Give two examples

Answer 7

Parasites than contain an apical complex (which allows parasite to enter host cells)

Plasmodium and toxoplasma

Question 8

Give the life cycle of a Plasmodium. What disease do they cause?

Answer 8

Cause malaria

Parasite reproduces inside the mosquito (the DEFINITIVE host)

Sporozoites are injected into humans when the mosquito feeds

These then enter the liver

Undergo rapid reproduction to form merozoites

Merozoites penetrate RBCs

Merozoites divide inside RBCs to form trophozoites

Continue to infect RBCs and when they rupture the cell, it causes a fever

Some trophozoites can mature to then form gametocytes

Mosquito can then take up the gametocytes

These go into the gut of the mosquito and burrows in to form the zygote

Zygote form the oocyte

The cycle repeats

Question 9

What is Trypanosoma brucei?

Answer 9

A parasite

Causes sleeping sickness in humans and nagana in hoofed animals

Have variant surface glycoproteins which they can keep changing to prevent the host from having an immune response

Question 10

What are the two subspecies of Trypanosoma brucei?

Answer 10

gambiense = transfers fly-human-fly and causes death after 2-3 years

rhodesiense = transfers fly-game-fly and causes death after 6-18 weeks

humans can be introduced to the rhodesiense cycle (zoonosis)

Question 11

What fly spreads